Main Burner Operation Testing - Bock Water heaters 38W-155 Service Manual

W-Series
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
Condition :
Main burner will not light.
Ignition module LED is "ON"
Is pilot lit?
Y
Does module continue to
spark with pilot lit?
N
Disconnect "brown" wire from
"MV" terminal of ignition module.
Is there 22-27 volts AC across
"MV" terminal of ignition module and
ground? (see photo 14)
Y
Reconnect brown wire
to ignition module.
Disconnect "brown" wire lead
from "MV terminal of gas valve.
Is there 22-27 volts AC across
"brown wire lead and ground?
(see photo 15)
N
Check wire harness for damage
or loose connections. Repair or
replace as needed.
10
DANGER
N
See "pilot will not light." (page 8)
See "pilot lights, no flame signal."
Y
(page 9)
Be sure module LED is "ON",
pilot is lit and module is not sparking.
N
Recheck voltage across "MV Terminal
of ignition module and ground.
Is voltage present?
Check incoming gas pressure to
Y
gas valve. If okay replace
gas valve.
Service Procedure 24-III

Main Burner Operation Testing

CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
Ground
14
N
Y
Brown wire disconnected from
"MV" terminal of gas valve
15
Replace ignition module.
Ground lug of gas valve
Disconnect "brown"
wire from "MV"
location of ignition
module.
Check voltage from
"MV" terminal of
ignition module and
ground.